The major objective of this invention is to produce wood composite structures that have a combination of aesthetically appearing durable finished surfaces and fire retardancy. This particular combination has long been sought and many methods have been described to achieve such an effect.
The wood composite structures of this invention having the hard durable surfaces means that the panels have been treated so that the treatment is throughout the wood and when the wood is surface finished, the durability and aesthetic appearance of the wood surface is not lost. Further, the fire retardancy of such wood composites is not lost in any degree whatsoever.
There has long existed a hiatus in manufactured wood products between aesthetically appearing wood surfaces and adequate fire retardancy.
Many approaches have been made to achieve wood products which would have both essential properties yet be capable of retaining both essential properties during construction utilizing such wood products.
Heretofore, when wood products were manufactured having both fire retardancy and aesthetically appearing surfaces, the wood products could not be further finished because of the risk of decreasing the aesthetic appearance or the fire retardance or both. In other words, if the wood products needed to be sanded or otherwise finished after being put in place, the fire retardancy was adversly affected because of the removal of some of the fire retardant from the surface thereby exposing raw wood having a greater tendency to ignite.
Further, impregnation of wood products at the factory to ensure adequate fire retardancy often leads to finishes which can not be made to have aesthetically appearing surfaces.
Finally, wood composites have been made which have an extra layer to the composite which is fire retardant. These fire retardant layers, however, have to be overlaid with decorative layers in order for the panel to be used for decorative purposes. If this is done, then the overlay is either non-fire retardant or is subject to the problems discussed above. Such wood composites can be found, for example, in U.S. Pat. No. 1,987,506 issued Jan. 8, 1935 to James R. Fitzpatrick. The panels are constructed such that there is incorporated a sheet of asbestos between a sound damping soft core and a composite made up of a poplar or soft wood core and a decorative wood overlay. In the event of a fire, the soft sound damping core would be protected but the outer composite of softwood core and decorative overlay would probably be consumed.
U.S. Pat. No. 3,501,339, issued Mar. 17, 1970 to Arthur Gurgiolo shows a method of treating wood products with specific flame retardant materials.
Gurgiolo allegedly solves the problem discussed above, that is, the problem of destroying fire retardancy when wood products containing fire retardants on their surfaces are cut to expose raw wood surfaces, by treating such woods with alkyl or aryl halogenated phosphites or phosphonates. Gurgiolo, however, does not indicate or discuss the effect of the treatment as regards fine finishing of the wood after it is impregnated. The essence of the patent seems to be the fire retardancy and preservation of rough woods such as would be used for building construction. Compatibility of the fire retardants with other impregnation materials is not contemplated or discussed therein.
U.S. Pat. No. 3,817,822, issued June 18, 1974 to David Haddon Dawes describes the pre-impregnation of two panels and their subsequent gluing together via the use of a polyethylene based glue to form a composite which is fire retardant. The patent describes the added advantage of having a glue which is not affected by the use of fire retardants in the wood panels. The patent does not describe the use of fire retardants with wood that requires fine finishing nor does it describe what one needs to do to acquire woods having both fire retardancy and the ability to be finished.
Thus, the problem of having fire retardancy in a wood product which can be fine finished and still retain the fire retardant property, has not been resolved.
The following described invention has solved that problem.